Patent No. 3,356,427 discloses solid-lubricant bearings in which the rolling elements are separated by spacers containing a solid lubricating material, primarily molybdenum sulfide. The spacers are mounted on pins extending through the spacers and connected at their ends to two cage rings. Hence the location of the spacers is fixed relative to the cage, and, as wear occurs, contact between the rolling elements and the trailing spacers decreases. Another shortcoming arises by way of the inner races having confining annular flanges contacted by the rolling elements. Hence, when the rolling elements are cylindrical rollers, for example, the roller ends contact the race flanges without lubrication being provided to the roller ends by contact thereof with the lubricating spacers. The design of the spacers is also such that there is virtually only line contact between the circumference of the rolling elements and the lubricating spacers.
Thus, although the self-lubricating bearing disclosed in Patent No. 3,356,427 was an important step forward in the bearing art, it has shortcomings. These shortcomings are magnified when the bearings are subjected to high-temperature operating conditions, particularly when the bearing are subjected to repeated rotational reversals under load. They are also magnified when the resulting thermal expansion of the races as compared to that of the other parts results in expansion of the clearance between the rolling elements and spacers.